Function group tests internal

Alcohol/ aldehyde test with acidified dichromate explanation=

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This is a redox reaction. The acidified dichromate causes any 1º alcohols to oxidise into an aldehyde, any 2º alcohols to oxidise into ketones and any aldehydes to oxidise into carboxylic acids. During this reaction some ‘H’ atoms are lost. The colour change in the dichromate from orange to green is due to the chromium in the dichromate being reduced to Cr(3+charge) ions.

Cr207(2- charge) /H+ / heat

Cr(3+ charge)

Carboxylic acid test with sodium carbonate explanation=

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The carboxylic acid will react with the sodium carbonate in a neutralisation reaction. A sodium carboxylate salt is formed as the organic product. Carbon dioxide is also produced as a gas, as well as water.

Na2CO3

H20 + CO2

slay

slay

Aldehyde test with Benedict’s solution explanation=

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This is a redox reaction. The copper (II) ions in the Benedict’s solution are reduced to copper (I) ions. This changes the colour from blue to brick red when the aldehyde is oxidised to a carboxylic acid.

Cu(2+ charge)(aq) / heat

Cu20